Field of the Invention
The present invention concerns a device to prevent the drying of nozzles of a machine for the preparation of fluid coloring products. Typically, the device according to the present invention is applied in machines, also called dispensers, which use a delivery head provided with a plurality of nozzles, to selectively dispense defined quantities of coloring agents, or pigments, for example liquids, into a base product for paints, varnishes, enamels, inks or suchlike, contained in a receptacle, and to thus obtain a finished product with a desired shade of color.
Description of Related Art
In the field of machines for preparing fluid coloring products, such as paints, varnishes, enamels, inks or suchlike, using the selective and controlled delivery of colored pigments, through a delivery head provided with one or more nozzles, even several dozen, it is known to provide a device which prevents the nozzles from drying, above all when the machine is not operating.
A device to prevent the nozzles in a dispensing machine for fluid coloring products from drying out is known from the American patent U.S. Pat. No. 5,842,641, which comprises a cup element horizontally mobile between an inactive position, distant from the delivery head, and an operating position in which it is in contact with the delivery head. A buffer disc of absorbent material, impregnated with water or a solvent, is disposed in the cup element. The buffer disc is vertically mobile between an inactive position, distant from the nozzles, and an operating position, near to the tips of the latter, in order to create a humidifying chamber with a reduced volume.
This known device, however, has the disadvantage that it is rather complex, because it needs two movement mechanisms, one to move the cup element horizontally and the other to move the buffer disc vertically.
Another device to prevent the nozzles in a machine to prepare fluid coloring products from drying out is described in WO 2005/107956A1 in the name of the Applicant. This device comprises elements for conveying a stream of air in the zone under the nozzles in order to create a different atmosphere from the environmental atmosphere, and to determine conditions which do not cause the nozzles to dry out when they are in their non-operating condition. The device also comprises a covering element for the delivery head, which is applied to selectively create a closed chamber with controlled atmosphere around the head, normally when the machine is in a non-operating condition for a certain time. The cover does not in fact function as an anti-drying member but only to close the chamber in which the desired atmosphere has been created by a controlled stream of air.